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Xochitecatl [ʃot͡ʃiˈtekat͡ɬ] is a pre-Columbian archaeological site located in the Mexican State of Tlaxcala, 18 km southwest of Tlaxcala city. [1] The major architecture dates to the Middle Preclassic Period (1000–400 BC) but occupation continued, with one major interruption, until the Late Classic , when the site was abandoned.
The bacterial DNA is not packaged using histones to form chromatin as in eukaryotes but instead exists as a highly compact supercoiled structure, the precise nature of which remains unclear. [6] Most bacterial chromosomes are circular, although some examples of linear chromosomes exist (e.g. Borrelia burgdorferi). Usually, a single bacterial ...
Acetogenesis is a process through which acetyl-CoA [1] or acetic acid is produced by anaerobic bacteria through the reduction of CO 2 via the Wood–Ljungdahl pathway.Other microbial processes that produce acetic acid (like certain types of fermentation or the oxidative breakdown of carbohydrates or ethanol by acetic acid bacteria) are not considered acetogenesis.
Structure of a teichoic acid repeat unit from Micrococcaceae Structure of the lipoteichoic acid polymer. Teichoic acids (cf. Greek τεῖχος, teīkhos, "wall", to be specific a fortification wall, as opposed to τοῖχος, toīkhos, a regular wall) [1] are bacterial copolymers [2] of glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds.
Glycocalyx is produced by many bacteria to surround their cells, [89] and varies in structural complexity: ranging from a disorganised slime layer of extracellular polymeric substances to a highly structured capsule. These structures can protect cells from engulfment by eukaryotic cells such as macrophages (part of the human immune system). [90]
This gave undersea mats their typical modern structure: an oxygen-rich top layer of cyanobacteria; a layer of photosynthesizing purple bacteria that could tolerate oxygen; and oxygen-free, H 2 S-dominated lower layers of heterotrophic scavengers, mainly methane-emitting and sulfate-reducing organisms.
The general secretion (Sec) involves secretion of unfolded proteins that first remain inside the cells. In Gram-negative bacteria, the secreted protein is sent to either the inner membrane or the periplasm. But in Gram-positive bacteria, the protein can stay in the cell or is mostly transported out of the bacteria using other secretion systems.
Biofilm growth is associated with an escalated level of mutations and horizontal gene transfer which is promoted in due to the packed and dense structure. Bacteria in biofilms communicate by quorum sensing, which activates genes participating in virulence factors production. [25] [26] Biofilms are the product of a microbial developmental ...